A 13 year old little brother had grown up around the lives of crooked cops, gangsters,corrupted politicians, a broken family, and a brother who is hated by them all. Will the little fella help his brother, abandon him, or do absolutely nothing?

As said above, the main problem with this logline is that we have absolutely no sense of what the protagonist's goal is. Also with the last part I feel it would be more effective if it was just an ultimatum. Will he come to his brothers aid or abandon him? The bit about doing absolutely nothing sounds uninteresting. It isn't the best way to end your logline. You want to leave with a punch.

And who in the cast of the crooked and corrupt is the designated antagonist, the primary opponent who stands in the way of his goal?

How about this?

"A teenage boy who grew up in a family of criminals and corrupt politicians struggles to choose between the only life he knows and coming to the aid of his beloved older brother, a man totally opposed to the family?s values."